Omar, Hadi A. A. (1987) Synthesis and studies of metal complexes of new azamacrocyclic ligands. PhD thesis, University of Warwick.

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Abstract

The macrocycles referred to in this summary are identified in the frontispiece.

Ten new azamacrocyclic ligands have been synthesised and characterised, together with some of the metal complexes they form with the divalent metal ions Ni²⁺, Cu²⁺, Zn²⁺, Pb²⁺, and Cd²⁺. The pyridine-containing tetra-azamacrocycle L¹, the related N-functionaIised ligands L¹³ and L¹⁷-L¹⁹, the penta-azamacrocycles L⁵-L⁷, as well as the piperidine-containing tetra-azamacrocycle L⁴, and the binucleating octa-azamacrocycle L¹⁰ were investigated.

Diamagnetic square-planar complexes, [Ni(L)] [ClO₄]₂ (L = L¹ and L⁴), were isolated, and the three isomers formed by L¹ were separated and characterised by ¹³C n.m.r. The structure of
unsymmetric [Ni(L)] [ClO₄]₂ was established by x-ray crystallography. Paramagnetic Ni²⁺ complexes of L¹ were found which were either square-pyramidal [Ni(L¹ )X]ⁿ⁺ (X = unidentate ligand; n = 1 or 2), or cis-octahedral [{Ni(L¹)}₂OX]²⁺ (OX = oxalate ion) with a tetradentate bridging oxalate group. Structures of the oxalato-complex, and the five-co-ordinate complexes with X = CI⁻ and dimethyl sulphoxide (DMSO), were established by x-ray crystallography.

Five- and six-co-ordinate complexes of L⁵ -L⁷ were prepared of the type [M(L)]²⁺ (M = Cu, L = L⁵ -L⁷, M - Zn, L = L⁷, M = Cd, Pb, L = L⁶-L⁷) and [M(L)(DMSO)]²⁺ (M = Ni, L = L⁶ and L⁷ , M = Zn, L = L⁶ ). A crystal structure of [Zn(L⁷)][ClO₄]₂ shows that the geometry around the zinc ion is a distorted trigonal bipyramid, with the pyridine N-atom in the trigonal plane, and with a C₂ rotation axis passing through the Zn and pyridine N-atoms, and bisecting the C-C bond furthest removed from the pyridine ring.

The large ring octa-azamacrocycle L¹⁰ forms homobinuclear complexes of the type [M₂(L¹⁰)]⁴⁺ (M = Ni, Cu, Zn), and a heterobinuclear complex [NiCu(L¹⁰)]⁴⁺ was also separated.

Of the complexes formed by the pendent-arm macrocycles L¹³ and L¹⁷-L¹⁹, the structures formed by two of them were established by x-ray crystallography. In [Ni(L¹³)OClO₃][CIO₄] the Ni²⁺ ion Is octahedral with co-ordinated perchlorate ion in a trans-position to the co-ordinated pendent-arm, and in [Cu(L¹⁹H₂)CI]CI the complex is a distorted trigonal bipyramid with only one of the two pendent carboxylate groups co-ordinated, and with the N-atom furthest from the pyridine ring protonated and non-co-ordinating.

The ligands and diamagnetic complexes were studied by ¹H and ¹³C n.m.r., and in several cases evidence found for more than one isomer in solution. The Ni²⁺ and Cu²⁺ complexes were studied by u.v.-visible spectroscopy, and all of the complexes examined by fast atom bombardment (f. a. b.) mass spectroscopy. Magnetic moments of the paramagnetic complexes were measured at room temperature, and most of the compounds analysed for their elemental composition.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Macrocyclic compounds -- Synthesis, Ligands, Metal complexes
Official Date:	September 1987
Dates:	Date Event September 1987 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Moore, Peter (Professor of chemistry)
Sponsors:	Jāmiʻat al-Fātiḥ
Format of File:	pdf
Extent:	xii, 184 leaves : illustrations, charts
Language:	eng

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